This invention relates to a computer system and a method of managing a storage system and, in particular, to reallocation of resources in the storage system.
In a known implementation of a storage system that provides hosts with volumes, the storage system configures tiered pools each composed of a plurality of media different in performance capability and allocates virtual volumes formed from the pools to the hosts (for example, refer to Patent Literature 1).
The storage system analyzes I/O (Input/Output) load from the host to the virtual volume, and automatically allocates pages with high I/O load to a tiers of high levels, which are composed of resources configured with high-performance high-cost disks, and the other pages to tiers of lower levels, which are composed of resources configured with lower-performance lower-cost disks. This configuration efficiently achieves satisfaction of performance requirements at lower TCO (Total Cost of Ownership).    Patent Literature 1 US 2007/234109 A